1. Field of the Invention
This invention relates to dyeable smooth-dry crosslinked cellulosic material and its creation by means of contacting the crosslinked material with an alkali swelling agent prior to dyeing.
2. Description of the Prior Art
Cellulosic fabrics do not possess smooth-dry (durable press or wash wear) performance or dimensional stability. In order to acquire these properties, cellulosic fabric requires a chemical finish. The chemical agents used in these processes are known as crosslinking agents. Examples of some agents are dimethylol dihydroxyethyleneurea (DMDHEU) or dimethylol propylcarbamate (DMPC).
While treatment of cellulosic fabric with a crosslinking agent does make the fabric smooth drying and dimensionally stable, it reduces the dyeability of cellulose by causing the cellulosic fibers to become fixed in a collapsed state upon their being cured at elevated temperature. Therefore, modern textile processes require fabric to be dyed first and then finished for smooth dry performance. When fabrics are crosslinked with common and readily available agents, such as DMDHEU or DMPC, subsequent dyeing has been unsuccessful.
Previously, crosslinking agents and reactive additives have been utilized as a route to dyeable crosslinked fabrics. U.S. Pat. No. 3,788,804 teaches the use of crosslinking agents and hydroxycarboxylic acids to form crosslinked fabrics with acidic grafts, and dyeing the fabrics with basic dyes. Also, U.S. Pat. No. 3,807,946 teaches the use of crosslinking agents and a reactive additive such as triethanolamine to form a crosslinked fabric with a grafted amine and dyeing such with an acid dye. U.S. Pat. No. 3,853,459 utilizes a treatment of crosslinking agent and polymer to form a durable-press fabric with a polymeric treatment and dyeing with a disperse dyestuff.
These patents have in common the teaching of dyeing modified cellulosic fabrics with non-cellulosic dyestuffs. Consequently, the performance of these dyes on a cellulosic substrate is not as good as cellulose dyed with normal dyestuffs such as direct or reactive dyes which are usually used on cellulosic fabrics.
U.S. Pat. 4,780,102 teaches improved dyeing properties for cotton finished with both a crosslinking agent and polyethylene glycol. Fabric treated according to this method can be dyed with dyes normally used with untreated cotton, such as direct and reactive dyes, but color strength is adversely affected with the increasing molecular weight of the dye. Usually, the color strength of the finished-crosslinked material is not as good as that of the untreated cotton. Also, such fabric cannot be dyed with acid dyes nor with reactive dyes under acidic conditions.
Pierce et al. [Tex. Res. J. 34:552-558 (1964)] have shown that glycol ethers in the finishing formulation are capable of propping open the cellulosic fiber during the curing reaction so that crosslinking occurs with the cotton in a swollen rather than collapsed state. To applicants' knowledge there are however no teachings in the literature on the alkali treatment of cotton for improving dyeing characteristics after finishing fabric with a crosslinking agent.